F UN ARIA [H YGROMETRICA 137 



culum, showing its teeth, i. These teeth are in a 

 double row; they form the peristome (Gr., peri, around; 

 stoma, mouth). They are hygroscopic, and in wet 

 weather close the mouth of the capsule, preventing the 

 spores from escaping. When the air is dry, they turn 

 back, open the mouth, and set the spores free — a very 

 remarkable device to regulate spore-dispersal, and to 

 insure that the spores are freed in dry condition, so that 

 they may be dispersed far and wide by wind. 



The capsule is at first green; it becomes brown at a 

 later stage. The seta, or stalk, is reddish and sinuous. 

 There is a remarkable feature in the base of the green 

 capsule; stomata, or air pores, occur in its epidermis, 

 and are related to a zone of cells containing chlorophyll. 

 It is thus apparent that this part of the capsule performs 

 a nutritive function, and shows that the sporophyte is 

 not utterly dependent upon the gametophyte for sup- 

 plies. We noted a similar feature in the Anthocerotes 

 (p. 128), but it does not appear in other Liverworts. 



The ripe spore contains chlorophyll and oil. When it 

 germinates, on the strength of its reserves, it does not 

 immediately produce an ordinary Moss plant. The 

 product of its germination is seen in Fig. 17, Plate IV., 

 in which r is the germinating spore and the protonema 

 (p. 129) which issues from it; s stands for rhizoids. The 

 spore at first produces two filaments, one of which 

 becomes a rhizoid, while the other creeps over the 

 ground, and sends out branches; the ordinary gameto- 

 phytes, or Moss plants, arise from branches of this proto- 

 nema, and a protonema formed from a single spore may 

 yield a number of plants. This curious development 

 certainly forms an excellent means of vegetative propa- 



18 



